Variable pump for fuel injection supply



Jan. 28, 1964 H. R. SCIBBE VARIABLE PUMP FOR FUEL INJECTION SUPPLY FiledSept. 22, 1961 2 Sheets-Sheet 1 IN V EN TOR. flara/a R. 5c z'fihz Jan.28, 1964 H. R. SCIBBE VARIABLE PUMP FOR FUEL INJECTION SUPPLY FiledSept. 22. 1961 2 -Sheet 2 @m Q wN m5 (w R A M W H.

United States Patent 3 119 349 VARHABLE PUMP FUR FUEL INJECTION SUPPLYHarold R. Scihbe, Chardon, Ohio, assignor to Thompson Raine WooldridgeInc, Cleveland, Ohio, a corporation of Ghio Filed Sept. 22, 1961, Ser.No. 140,012 2 Claims. (Cl. 103-38) The present invention relates toimprovements in fuel injection systems for high speed, four cycle, sparkignition internal combustion engines and to an improved variabledisplacement fuel pump for a fuel injection system.

The invention contemplates the provision of a system employing avariable output pump having a plurality of pistons operating incylinders at controllable stroke lengths. The pump delivers to adistributor which provides for periodic uniform releases of the fuel tolines leading to fuel injectors. The distributor is driven from theengine and a shaft for driving the pump is mechanically connectedthrough gearing to the distributor to be driven at a speed ratiorelative to the distributor which cannot be expressed exactly in wholenumbers so that starved or rich phases in the pump operation will notcontinually occur at releases to the same injectors but will move on toother injectors. The pump has a plurality of radially extending pistonsembodying an improved seal with the cylinder wall, and the stroke of thepistons is controllable by a plunger in the pump shaft which varies theeccentricity of a simplified driving head. The plunger is spring loadedto increase the delivery of the pump and an arm acts against the springto obtain a positive movement for reducing the pump delivery.

It is an object of the present invention to provide an improvedsimplified reliable variable delivery pump particularly adapted for usein a fuel delivery system for fuel injection engines.

Another object of the invention is to provide an improved controlmechanism for varying the output of a reciprocating fuel pump employingradially extending pistons driven by a centrally located eccentric.

A still further object of the invention is to provide an improved sealfor a fuel pump between the piston and the wall of the cylinder.

A further object of the invention is to provide an improved pumpconstruction for a fuel system wherein the formation of air and vaporpockets is reduced.

A still further object of the invention is: to provide a simplifiedpiston and drive construction in a pump of a type having radiallyextending pistons driven by a centrally located oscillating eccentrichaving a variable eccentricity.

Other objects and advantages will become more apparent from theteachings of the principles of the invention in connection with thedisclosure of the preferred embodiment thereof in the specification,claims and drawings, in which:

FIGURE 1 is an end elevational view of a fuel delivery unit including apump and a distributor constructed in accordance with the principles ofthe present invention;

FIGURE 2 is a vertical sectional view taken substantially along lineIIII of FIGURE 1;

FIGURE 3 is a vertical sectional view taken substantially along line IIIIII of FIGURE 2;

FIGURE 4 is a horizontal sectional view taken substantially along lineIV-IV of FIGURE 2;

FIGURE 5 is an enlarged fragmentary detail view showing parts of theseals for the pistons before assembly; and

FIGURE 6 is a fragmentary enlarged detail view showing the seal parts ofFIGURE 5 after assembly.

As shown on the drawings:

FIGURE 2 illustrates a mechanism having a pump 10 with a variabledelivery for pumping fuel. The fuel flows to a distributor 11 which atintermittent periodic intervals releases the pumped fuel to individualfuel injectors, not shown, which supply an internal combustion engine.The fuel flows from the pump to the distributor through a conduit means12 and communicating with the conduit means is an accumulator 13 whichcollects the fuel from the pump between distributor releases andcompletely discharges its collected fuel during the periods ofdistributor release.

Also communicating with the conduit means 12 is an enrichment device 15which is filled with fuel from the metering piunp 11 and selectivelydischarges this fuel to the distributor 11 when the engine isaccelerated.

The metering pump 10 and distributor 11 are incorporated in a unithousing 16, FIGURES 1 and 2, made up of parts which are suitably clampedtogether such as by cap screws or bolts with the parts having gasketstherebetween. These parts need not be described in detail inasmuch astheir construction will be apparent from the drawings and the entitymaybe generally referred to as the housing 16. The distributor 11 andaccumulator 13 are carried in housing part 16a and plate 16b, and themetering pump in parts 160, led. Pumping chambers and valves are carriedon side housing projections 16e, FIG- URES 3 and 4. The housing isadapted to be suitably mounted on an engine tobe driven by the engine inthe position shown in FIGURES 1 and 2 such as by being connected to thetiming shaft. The mechanism has a distributor shaft '17 which is drivenat one half the speed of an engine to which fuel is delivered so that ina four cycle engine the distributor 11 will release fuel once for oneinjection per four stroke cycle of the typical multicylinder engine.

Fuel is received through a line connected to a fuel intake opening 18 inthe housing 16 and usually fuel will be delivered to the apparatus froma fuel tank by a supply pump so that the intake 18 will receivepressurized fuel. The distributor is connected to individual fuel lines19a which lead to the injectors.

The metering pump 1ft is driven from the distributor shaft 17 which issupported in the housing 16 in a ball bearing assembly 18' and acylindrical bearing surface 19. A circular sealing ring 29 is positionedaround the shaft in the housing to prevent the escape of lubricant anda. ring 21 is also positioned around the shaft to prevent the escape offuel from the distributor 11, as will later be described.

The pump 10 is driven by a gear 22 on the shaft 17 driving a gear 23pinned to the pump shaft 24 which is supported in a ball bearingassembly 25.

The ratio of the gear 22 on the shaft 17 to the gear 23 on the pumpshaft is preferably one which cannot be expressed exactly in wholenumbers, such as 23/30 or 30/23; 25/28 or 28/25; 20/33 or 33/20.Inasmuch as the pump is a piston type, such fractional gear ratios willpreclude the possibility of any one piston consistently delivering fuelthrough the same port of the distributor and hence to the same enginecylinder. If small differences exist between the pistons, pistonchambers, piston stroke links or seals of the pumping element a slightinequality of fuel delivery may occur between pistons and this will notconsistently result in the inequality being reflected in the fueldelivered to one or more engine cylinders but will move through thesequential injections to all of the cylinders. For example, enginefailures due to consistently lean mixtures on one cylinder of the engineare prevented; While excessively rich or lean injections could occur dueto manufacturing differences, these conditions will move through all ofthe cylinders of the multicylinder engine.

The bearing 25 for the pump shaft 24 and the pump pistons are lubricatedthrough a lubrication connection 26 in the housing and lubricant flowsthrough suitable passages through a passage 27 to the bearing 25 andthrough passages such as 28 leading to the individual pump pistons andtheir seals. Lubricant is also delivered to the hollow chamber 33 whichcontains the mechanism for driving the pump pistons.

As shown in FIGURES 2 and 3, the pump is provided with three radiallyextending pistons 29, 3t) and 31 slidably supported in radially boredcylinders 29a, 3% and 31a in the housing 16. An odd number of pistonsare provided and a greater number may be employed if desired retainingan odd number. The pistons are movable radially outwardly in a dischargestroke and radially inwardly in an intake stroke and are urged inwardlyby springs such as 32 surrounding the inner ends of the pistons andseated in annular recesses in the wall of the chamber 31. Split snaprings 34 seat in annular grooves in the pistons to hold washers againstwhich the springs engage. Inasmuch as the construction of each piston isthe same, the arrangement of the piston 30 only need be described indetail. The pistons are uniformly cylindrical in shape and size and aretherefore inexpensive and simple to construct and can be formed out of acontinuous length of stock material.

The pistons are driven by a head 35 eccentrically carried at the lowerend of the pump shaft 24. The head 35 rotatably supports a roller 36which is rotatably mounted on a stud 35a on the head and the roller 36rolls on the stud to reduce friction between the roller and pistons.

The head 35 is carried in a radially extending supporting slot 37 on theshaft 24 and its eccentricity with respect to the axis of the shaft iscontrollable by a bell crank 38 supported on the shaft. The lower arm ofthe bell crank is held in a recess 39 in the head 35 and the upper armof the bell crank 39 is received in a recess 4% in a plunger 4-1coaxially carried in the hollow center of the pump shaft 24. A cross pin41a extends across through an axially elongated slot 41b in the plunger41 and the pin 41a is mounted in the shaft 24. This pin 41a alsofunctions to lock the gear 23 to the pump shaft. A spring 42 in anaxially extending recess in the end of the shaft 24 engages theunderside of an enlarged head 410 of the plunger 41 to urge it to theleft, as shown in FIGURE 2. This tends to move the head 35 to increasethe eccentricity thereof and increase the pump delivery. The action ofthe spring 42 is resisted by an arm 43 hearing on the upper end of thehead of the plunger 41 and mounted on a shaft 44. The shaft 44 isconnected to a fuel control mechanism which operates an arm 45, FIGURE1, on the shaft 44.

Spring 42 on coaxial plunger 41 eliminates lash in the external controllinkage that actuates arm 45. It tends to minimize metering hysteresisconunon to manifold pressure sensitive controls. While in theillustrated design the spring urges the coaxial plunger to increase theeccentricity of the drive and the stroke of the pistons, the oppositeeffect could also be employed. For other applications, the spring couldbe positioned to hold the drive concentric and the pistons at zerostroke. The external control linked to the plunger control member (arm45) would then move to increase eccentricity and piston stroke.

The fuel control mechanism will determine the displacement and output ofthe metering pump 10 and is operated in accordance with various factorsof engine conditions such as the intake manifold pressure and enginetemperature. A manual input signal is also provided by an accelerator,not shown and the fuel control mechanism is also not shown inasmuch asvarious devices may be employed as will be appreciated by those skilledin the art.

Each of the pump plungers are sealed by an O-ring 47 in an annulargroove 47a in the housing, as shown in FIGURES 2, 3, and 6. Asparticularly shown in FIG- URES 5 and 6, the width W of the groove 47ain an axial direction is greater than the cross sectional diameter W ofthe uncompressed O-ring 47. The diameter D of the base of the groove 47ais less than the outer diameter D of the O-ring 47. The diameter D ofthe piston 35 is less than the inner diameter D of the O-ring 47. Whenassembled, as shown in FIGURE 6, the radial compression of the base ofthe groove 47a on the outer sunface of the O-ring forces the innerdiameter of the ring to contact the cylindrical piston surface. Thedimensions of the O-ring, O-ring groove, and piston are designed so thatthe contact of the inner diameter of the O-ring with the piston issufiicient to seal against the fuel pressure but light enough to preventexcessive friction during reciprocation of the piston within the seal.The axial Width of the O-ring groove prevents axial compression of theO-ring. The cylindrical bore 30a in which the piston slides is relievedat its outer end 3% so as to be of a slightly larger size than the innerend of the bore to thereby prevent scratching contact between the pistonand the cylinder where the piston slides through the O-ring '47. Thisinsures that the piston will retain its finish at that location and notwear the O-ring but retain a good seal. Also, the lubricant passage 28opens to the cylinder inwardly of the O-ring so that the piston issubjected to lubricant at all times Where it slides through the O-ring.

As shown in FIGURES 2 and 3, the fuel enters the intake 18 of thehousing and flows through a passage 49 that forms a loop. Off this loopare branch passages 50, 51 and 52 for supplying pumping chambers 48 atthe end of the pump pistons. Fuel intake into the pump chambers 48 flowsthrough an intake port 510 past a check valve, FIGURE 4, having a ballcheck 53 held by a spring 54 against a seat 55 so as to close the intakepassage when the pump piston moves outwardly. Flow out of the pumpingchamber 48 is through a port 56a past a ball check valve 5611 whichcloses during the intake stroke of the piston. The ball check valve 56bis held against a valve seat 55c by a spring 56d. The pumping chambers43 and the check valves are conveniently contained in housingprojections 16a, FIGURES -1 through 4, mounted on the housing at theends of each of the pump pistons.

Delivery from the pumping chamber 48 is through a passage 56 leading upinto a chamber 57 in which is lo: cated a distributor plate 58. Thepassage 56 and the chamber 57 constitute the conduit means leading fromthe pump discharge to the distributor.

It is to be noted that the pumping chamber receives fluid through theport 51:: and delivers fluid through the port 56a. These ports and thepassageways connected thereto are arranged so that fluid flow throughthe pumping chamber 48 is in an upward direction thus facilitating theescape flow of fluid vapor and entrained air through the chamber. All ofthe fluid passages in the pump are designed to prevent the trapping :offuel vapor or entrained air in the pumping elements. This makes the pumpself-purging of vapor and air and greatly reduces the number of pumprevolutions required to purge a vapor locked pump.

As shown in FlGURE 2, a distributor valve or valve disc 58 has a flatsmooth undersurface which sealingly slides against a surface 59 in thechamber 57 and is held downwardly by a spring 60 and is driven by theshaft 17. Below the distributor valve 58 in the distributor plate 16bare a series of evenly spaced circumferentially arranged relief ports 62which conduct fuel each time an elongated port 61 in the distributorvalve 58 passes over them. This intermittently at even intervalsrelieves the fluid fuel from the distributor chamber 57 and the fuelsequentially flows out through the lines 19 to the individual injectors14.

The accumulator 13 is in communication with the conduit means 12 betweenthe pump and distributor has an expansible chamber in the form of acylinder 63 in which is located a piston 64. The piston is spring loadedby a spring 66 which urges the piston 64 in a direction to discharge thefuel from the chamber 63-. An annular piston seal 65 surrounds thepiston.

The spring 66 has a natural frequency greater than the accumulatorexciting frequency, namely the opening and closing of the successivedistributor ports. The accumulator thus empties itself for each releaseof the distributor.

The accumulator 13 is located below the distributor chamber and in aposition so that air or fuel vapor cannot be trapped. The cylinder 63 isshown in a horizontal position below the distributor.

Also in communication with the distributor chamber 57, or in otherwords, in communication with the conduit means 12 between the pump anddistributor, is an accelerator chamber shown in the form of an elongatedcylinder 67. The chamber 67 communicates with the distributor chamber 57through openings '72 through the distributor plate. Within the chamber67 is a piston 65 having a piston ring 69. The piston is mounted on apiston rod 7t) suitably connected to an accelerator pedal, not shown.

Movements of the accelerator pedal to decelenate a low the chamber 67 tofill from fuel delivered by the pumplt). As the accelerator is moved inan accelerating direction, the piston 63 will force fuel out of thechambers 67 through the openings 72 which will cause the distributor todeliver an increased quantity of fuel to the engine. The distributorvalve 57 is held down against its smooth surface 59 by a coil spring 60and the how of fuel through the passages 72 :have no effect on thenormal operation of the distributor.

The use of this accelerator chamber 67 enhances the response of theengine to movements of the accelerator pedal without adding to the flowrate through the variable displacement pump :10. This therefore occurswithout sacrifice to the general fuel economy. It is also to be notedthat as the accelerator is release-d, the variable chamber 67 providesan escape chamber for the fuel in the distributor thereby enhancing therapid cut-off of fuel supplied to the engine as the accelerator isreleased to prevent delivering over enriched fuel to the engine andconsequent smoking and increase in smog effects.

While the fuel injection nozzles may be of various designs, the nozzle14 is shown schematically as including an injection opening 74 againstwhich seats a valve member 73 held against the opening by a tensionspring '75. The tension spring 75 is such that it opens at a lower fuelpressure than that required to depress the accumulator spring 65. Thuswith the accumulator discharge pressure being greater than the injectornozzle opening pressure, the injector will open as soon as thedistributor 11 releases the fuel and will stay open during the time theaccumulator piston 64 is emptying the accumulator chamber and during thetime the distributor ports are in alignment.

As a brief summary of operation, the power or distributor shaft 17 isdriven from the engine to provide a fuel release for each fuel intakestroke of the engine, and through the gears 22 and 23 drives the pumpit). 1 e delivery of the pump is varied by the arm 43 pushing down onthe plunger 41 which determines the eccentricity of the head 35 and thestroke of the pump pistons 29, 30 and 31. Fuel flows in through theintake 18 past the intake check valve 53 on the intake stroke of thepiston 30 and a check valve 56b, FIGURE 4, closes off the deliverypassage 56. On the delivery stroke of the piston fuel flows through thepassage 56 to the distributor chamber 57. As the distributor valve 58rotates quantities of fuel are intermittently released as the port 61successively aligns itself with the ports 62. The accumulator chamber 63receives fuel between port releases and discharges during the releaseperiods.

The multiple piston metering and pressure generating pump has anadvantage in freedom from high speed limitations that are placed on asingle piston injection pump that must reciprocate through one strokefor each cylinder of a multicylinder engine. The metering pump with arotary distributor has considerable manufacturing advantages over typesheretofore used requiring individual pistons, cylinders, valves andpassages all of which must be precisely matched to maintain distributionequality for each cylinder of a multicylinder engine.

The rotating distributor of the unit is normally driven at half enginecrank shaft speed to provide one injection per four stroke cycle of thetypical multicylinder engine. The metering and pressure generating pumpis gear driven from the rotary distributor shaft at a speed selected tobest suit several factors, although preferably driven at a speed ratiowhich is not an exact whole number, as above described. The factorswhich determine the speed at which the pump is driven include pumpperformance efiiciency and endurance reliability and the maximumdelivery required by the particular engine displacement. A significantadvantage is that the same pump unit may be used to accommodate enginesof different sizes. For example, to accommodate a passenger car engine,a pump constructed as shown but using five pistons was geared to make4.55 piston strokes for every two-engine revolutions. An identical unitwas used to fuel a much larger displacement engine by employing a gearratio that provided 5.5 piston strokes per two-engine revolutions.

The versatility of the system is shown in the pumping unit illustratedwherein three pistons are employed for the pump. By changes in pistondiameter, maximum piston stroke, and pumping element driving gears, athree piston pump is capable of fueling a small displacement cubic inch)compact car engine or a large displacement (540 cubic inch) lightaircraft engine. Cast housings, mechanical linkages and controls for therange of engine sizes remain identical effecting advantages inservicing, assembly, and reduction of manufacturing cost.

It is to be noted that the pistons are of uniform diameter so that theycan be made of cylindrical stock mate rial. The simple manner in whichthe return springs are attached, the support for the springs and overalldrive arrangement make a reliable inexpensive construction possible.

It will be understood that while the distributor usually is employed toaccomplish one fuel release and one injection per four stroke cycle itmay also be used to pro vide two injections per four stroke cycle. Thismethod of distribution halves the large fuel quantities required percycle and precludes the necessity for larger metering pump components.

Thus it will be seen that I have provided an improved pump anddistributor arrangement incorporating an improved pump and system whichmeets the objectives and advantages above set forth. The arrangementlends itself to a compact unit device capable of continued operationwithout adjustment.

The drawings and specification present a detailed disclosure of thepreferred embodiments of the invention, and it is to be understood thatthe invention is not limited to the specific forms disclosed, but coversall modifications, changes and alternative constructions and methodsfalling within the scope of the principles taught by the invention.

I claim as my invention:

1. A variable displacement fluid pump comprising,

a pump drive shaft,

a pump piston slidably mounted in a cylinder extending radially from thedrive shaft,

an eccentric drive having an element thereof in dn'ving relationship tothe piston and being 'adjustably connected to the shaft forcontroll-ably varying the eccentricity for reciprocating the piston inits cylinder,

a plunger slidably mounted coaxially with said shaft and non-yieldablyconnected to said eccentnic drive for changing its eccentricity withaxial movement relative to the shaft,

a spring engaging the plunger and urging it in a first axial directionto increase the eccentricity of the drive element and the stroke of thepiston,

an operating surface on said plunger facing in said first direction,

and a control member engaging said plunger surface and moving thepiunger against the spring for tie creasing the eccentricity of thedrive and the stroke of the piston for positive control in a directionto reduce the pump output.

2. A variable displacement fluid pump comprising,

' a pump drive shaft,

a pump piston slid-ably mounted in a cylinder extending radially fromthe drive shaft,

an eccentric drive having an element thereof in driving relationship tothe piston and being mounted on a slide on the shaft and having a bellcrank connected to the slide for positioning the drive elementeccentrically relative to the shaft,

3. plunger slidably mounted coaxially with said shaft and non-yieldablyconnected to said bell crank for changing the eccentricity of the driveelement with axial movement of the plunger relative to the shaft,

a spring engaging the plunger for urging it in a first axial directionto increase the eccentricity of the drive element and the stroke of thepiston,

a plunger surface facing in said first direction, and a control leverengaging said plunger surface and moving the plunger against the springfor decreasing the eccentricity of the cam and the stroke of the pistonfor positive control in a direction to reduce the pump output.

References (Zited in the file of this patent UNITED STATES PATENTS831,890 Plane et a1. Sept. 25, 1906 1,982,958 Kraus Dec. 4, 19342,257,854 Peterson Oct. 7, 1941 2,336,996 McDonough Dec. 14, 19432,370,383 Wallace Feb. 27, 1945 2,404,175 Holden et al. July 16, 19462,442,488 Fisk June 1, 1948 2,539,277 Schroepfer Ian. 23, 1951 2,661,729Reiners Dec. 8, 1953 2,746,442 Roosa May 22, 1956 2,795,195 Amblard June11, 1957 2,828,696 Wright Apr. 1, 1958 2,902,938 Ebert Sept. 8, 19593,019,738 Zubaty Feb. 6, 1962 3,077,872 Allen Feb. 19, 1963 FOREIGNPATENTS 449,429 Canada June 29, 1948 857,594 France Apr. 22, 1940713,778 Germany Nov. 15, 1941 569,759 Great Britain June 7, 1945 824,152Great Britain Nov. 25, 1958

1. A VARIABLE DISPLACEMENT FLUID PUMP COMPRISING, A PUMP DRIVE SHAFT, APUMP PISTON SLIDABLY MOUNTED IN A CYLINDER EXTENDING RADIALLY FROM THEDRIVE SHAFT, AN ECCENTRIC DRIVE HAVING AN ELEMENT THEREOF IN DRIVINGRELATIONSHIP TO THE PISTON AND BEING ADJUSTABLY CONNECTED TO THE SHAFTFOR CONTROLLABLY VARYING THE ECCENTRICITY FOR RECIPROCATING THE PISTONIN ITS CYLINDER, A PLUNGER SLIDABLY MOUNTED COAXIALLY WITH SAID SHAFTAND NON-YIELDABLY CONNECTED TO SAID ECCENTRIC DRIVE FOR CHANGING ITSECCENTRICITY WITH AXIAL MOVEMENT RELATIVE TO THE SHAFT, A SPRINGENGAGING THE PLUNGER AND URGING IT IN A FIRST AXIAL DIRECTION TOINCREASE THE ECCENTRICITY OF THE DRIVE ELEMENT AND THE STROKE OF THEPISTON, AN OPERATING SURFACE ON SAID PLUNGER FACING IN SAID FIRSTDIRECTION, AND A CONTROL MEMBER ENGAGING SAID PLUNGER SURFACE AND MOVINGTHE PLUNGER AGAINST THE SPRING FOR DECREASING THE ECCENTRICITY OF THEDRIVE AND THE STROKE OF THE PISTON FOR POSITIVE CONTROL IN A DIRECTIONTO REDUCE THE PUMP OUTPUT.